Rubbish is so thick in some areas that water is not visible and rats are able to live on top of the disgusting floating debris.

Not
only are some 1,400 athletes at risk of getting violently ill in water
competitions, but the tests indicate that tourists also face
potentially serious health risks on the golden beaches of Ipanema and
Copacabana.

The
survey of the aquatic Olympic and Paralympic venues has revealed
consistent and dangerously high levels of viruses from the pollution, a
major black eye on Rio's Olympic project that has set off alarm bells
among sailors, rowers and open-water swimmers.

The
first results of the study published over a year ago showed viral
levels at up to 1.7 million times what would be considered worrisome in
the United States or Europe.

At
those concentrations, swimmers and athletes who ingest just three
teaspoons of water are almost certain to be infected with viruses that
can cause stomach and respiratory illnesses and more rarely heart and
brain inflammation - although whether they actually fall ill depends on a
series of factors including the strength of the individual's immune
system.

Since
the release of the initial results last July, athletes have been taking
elaborate precautions to prevent illnesses that could potentially knock
them out of the competition, including preventatively taking
antibiotics, bleaching oars and donning plastic suits and gloves in a
bid to limit contact with the water.

But antibiotics combat bacterial infections, not viruses.

And
the investigation found that infectious adenovirus readings - tested
with cell cultures and verified with molecular biology protocols -
turned up at nearly 90 percent of the test sites over 16 months of
testing.

'That's
a very, very, very high percentage,' said Dr. Valerie Harwood, Chair of
the Department of Integrative Biology at the University of South
Florida. 'Seeing that level of human pathogenic virus is pretty much
unheard of in surface waters in the U.S. You would never, ever see these
levels because we treat our waste water. You just would not see this.'

While
athletes take precautions, what about the 300,000-500,000 foreigners
expected to descend on Rio for the Olympics? Testing at several of the
city's world-famous beaches has shown that in addition to persistently
high viral loads, the beaches often have levels of bacterial markers for
sewage pollution that would be cause for concern abroad - and sometimes
even exceed Rio state's lax water safety standards.

In light of the findings, Harwood had one piece of advice for travelers to Rio: 'Don't put your head under water.'

Swimmers
who cannot heed that advice stand to ingest water through their mouths
and noses and therefore risk 'getting violently ill,' she said.

'Both
of them have pretty high levels of infectious adenovirus,' said
Harwood, adding that the virus could be particularly hazardous to babies
and toddlers who play in the sand....

Dr.
Fernando Spilki, the virologist and coordinator of the molecular
microbiology laboratory at Feevale University in southern Brazil whom AP
commissioned to conduct the water tests, says the survey revealed no
appreciable improvement in Rio's blighted waters - despite cleanup
promises stretching back decades....

In Rio, the
main tourist gateway to the country, a centuries-long sewage problem
that was part of Brazil's colonial legacy has spiked in recent decades
in tandem with the rural exodus that saw the metropolitan area nearly
double in size since 1970.

Even
in the city's wealthy areas, sewage treatment has lagged dramatically
behind, with so-called 'black tongues' of fetid, sewage-filled water
common even on the tony Ipanema and Leblon Beaches. The lagoons in the
fast-growing Barra da Tijuca region have been filled with so much sewage
dumped by nearby glass-and-steel residential towers that vast islands
of sludge emerge from the filthy waters during low tide. That lagoon
system, which hugs the Olympic Park and Athletes' Village, regularly
sees massive pollution-related fish die-offs and emits an eye-watering
sulfuric stench.

Promises
to clean up Rio's waterways stretch back decades, with a succession of
governors setting firm dates for a cleanup and repeatedly pushing them
back. In the city's 2009 Olympic bid document, authorities pledged the
games would 'regenerate Rio's magnificent waterways.' A promised
billion-dollar investment in cleanup programs was meant to be among the
games' most important legacies.

Once more, the lofty promises have ended in failure.

Just
over a month before the games, biologist Mario Moscatelli spent more
than two hours flying over Rio in a helicopter, as he's done on a
monthly basis for the past 20 years.

'It's
been decades and I see no improvement,'laments Moscatelli, an activist
who's the most visible face of the fight to clean up Rio's waterways.
'The Guanabara Bay has been transformed into a latrine ... and
unfortunately Rio de Janeiro missed the opportunity, maybe the last big
opportunity' to clean it up.